The present invention relates to flow regulators and particularly flow regulators employed for compressible fluid flow control and more particularly relates to such regulators which are supplied with a fluid pressure signal which is modulated by an electrically remote controlled valve for controlling the pressure applied to one side of a pressure responsive member. Regulators of this type typically have a moveable valve member attached to the opposite side of the pressure responsive member for controlling flow over a valve seat of the compressible fluid to be flow regulated.
Regulators of this type are utilized in motor vehicle fuel vapor emission control systems for controlling flow from a fuel vapor purge canister for communication with the charge air inlet of the vehicle engine. Purge control regulators of this type are known to utilize the engine manifold depression or vacuum as a fluid pressure signal source for the regulator. An example of such a regulator is that shown and described in U.S. Pat. No. 5,429,099 issued to Daniel L. DeLand.
In such known fuel vapor purge system flow regulators, problems have been experienced at certain levels of pressure in the vapor canister and at certain flow conditions in a connecting conduit between the canister and the flow regulator valve inlet. For a given length of conduit, pulses and rarefactions in the flow conduit have produced a standing wave which causes vibration of the pressure responsive member which in turn has produced a resonance in the conduit with the resultant tuning of the conduit. This resonating of the conduit between the fuel vapor canister and the regulator valve has produced an audible phenomenon known as "hooting" which is an undesirable noise in the system from the vehicle occupants' standpoint. A purge control regulator which addresses the hooting problem, is shown and described in a copending application Ser. No. 08/853,015, filed May 8, 1997 in the names of Barbara J. Erickson, Gerrit V. Beneker, Charles A. Detweiler and Daniel L. DeLand entitled "Dampening Resonance In A Flow Regulator" and assigned to the assignee of the present application. Another example of a fuel vapor purge regulator of the aforesaid type which addresses the "hoot" problem is that shown and described in a co-pending application Ser. No. 08/808,557, filed Feb. 28, 1997 in the name of Daniel L. DeLand, et al., entitled "Dampening Resonance In a Flow Regulator" and assigned to the assignee of the present invention.
Fuel vapor purge control regulators have also been designed to provide an electrically controlled valve for controlling fuel vapor by-pass flow around the pressure responsive member and eliminate atmospheric bleed flow to an intake manifold vacuum signal. An example of the latter type fuel vapor purge control regulator is shown and described in co-pending application Ser. No. 08/949,106, filed Oct. 10, 1997 entitled "Fuel Vapor Purge Control" in the name of Daniel L. DeLand, et al and assigned to the assignee of the present invention.
The latter type fuel vapor purge control regulator does not use a control signal based upon atmospheric bleed to intake manifold vacuum line and does not apply manifold vacuum directly to the control pressure side of the diaphragm. However, because the outlet of the regulator valve discharges to the engine intake manifold the regulator is subject to pulsations in manifold vacuum entering the regulator and causing resonant vibration and "hooting" in the system.
Thus, it has been desired to provide a way or means of dampening pressure pulsations or rarefactions in a flow regulator and to provide such dampening in a way that is low in manufacturing costs and does not adversely affect the function or calibration of the flow regulator.